Question

What is the formula for the compound that forms when magnesium bonds with phosphorus?

Answer 1

The formula would be `Mg_3P_2`. This would be an ionic compound.

Explanation:

First, we know this is an ionic compound because one of the elements is a metal.

From the periodic table or from the valence shells of the atoms, we can determine that magnesium forms an ion of `+2` charge. Also, phosphorus will form a `-3` ion.

The formula is based on combining these ions in the smallest ratio that results in a total charge of zero, because all compounds must be electrically neutral.

So, three `Mg^(2+)` ions and two `P^(3-)` ions result in a total of +6 and -6 charges, which gives us the zero total charge.

A compound with three magnesium ions and two phosphorus ions would be written `Mg_3P_2`